The undeveloped park is composed of three alluvial islands located in the middle of the Allegheny River northeast of Pittsburgh.

[2] The islands are just north of the boroughs of Oakmont and Plum, and southwest of Cheswick.

[3][4] Bridges for the Pennsylvania Turnpike (Interstate 76) and the Bessemer and Lake Erie Railroad Branch of the Canadian National Railway cross the Allegheny River at the middle island.

Camping is allowed on the islands and they are open for visits by groups such as the Boy Scouts and Venturing.

Allegheny Islands State Park is administered from the Region 2 Office in Prospect, Pennsylvania.